WEAK LINK FORMATION IN THALLIUM BOORIUM CALCIUM COPPER OXIDE

THE ELECTRICAL AND MATERIAL PROPERTIES OF HIGH TEMPERATURE SUPERCONDUCTING (HTSC) THIN FILMS HAVE IMPROVED DRAMATICALLYIN RECENT MONTHS. HOWEVER, A FABRICATION PROCESS CAPABLE OFPRODUCING JOSEPHSON JUNCTIONS IN FINITE YIELDS HAS YET TO BEDEVELOPED. SOME DEMONSTRATION DEVICES HAVE BEEN MADE WHICH INDICATE THAT THE 77 K NOISE LEVELS OF DC SQUIDS MADE FROM THALLIUM-BORIUM-CALCIUM-COPPER-OXIDE ARE LOW ENOUGH FOR MANYAPPLICATIONS. UNFORTUNATELY, A BASIC UNDERSTANDING OF THE PROCESSING PROTOCOL NEEDED TO REPRODUCIBLY ACHIEVE SUITABLE I-V CHARACTERISTICS IS LACKING. THE OBJECTIVE OF THIS PHASEI PROGRAM IS TO ESTABLISH THE BASIC PROCESSING TECHNOLOGY REQUIRED FOR RELIABLE WEAK LINK FABRICATION IN TLBACACUO. ANOVEL APPROACH WILL BE INVESTIGATED WHICH TAKES ADVANTAGE OF THE HIGH VOLATILITY OF THALLIUM OXIDE. THE CURRENT-VOLTAGE CHARACTERISTICS OF THE WEAK LINKS WILL BE MEASURED AND OPTIMUM PROCESSING CONDITIONS DEVELOPED. THESERESULTS WILL ESTABLISH THE FEASIBILITY OF REPRODUCIBLY FABRICATING WEAK LINKS IN MICROBRIDGES OF TLBACACUO. THESE RESULTS WILL PROVIDE THE KEY COMPONENT REQUIRED TO FABRICATEACTIVE HTSC DEVICES SUCH AS SQUIDS AND MICROWAVE MIXERS IN THE PHASE II PROGRAM.